U.S. patent application number 14/956030 was filed with the patent office on 2016-11-24 for non-condensable gas coinjection with fishbone lateral wells.
The applicant listed for this patent is CONOCOPHILLIPS COMPANY. Invention is credited to Bo CHEN, Qing CHEN, Thomas J. WHEELER.
Application Number | 20160341021 14/956030 |
Document ID | / |
Family ID | 56087592 |
Filed Date | 2016-11-24 |
United States Patent
Application |
20160341021 |
Kind Code |
A1 |
CHEN; Bo ; et al. |
November 24, 2016 |
NON-CONDENSABLE GAS COINJECTION WITH FISHBONE LATERAL WELLS
Abstract
Producing hydrocarbons by steam assisted gravity drainage, more
particularly utilizing conventional horizontal wellpair
configuration of SAGD in conjunction of infill production wells the
production wells comprising two or more fishbone lateral wells to
inject steam initially and then switch to NCG-steam coinjection
after establishing thermal communication between the thermal
chamber and infill well.
Inventors: |
CHEN; Bo; (Houston, TX)
; CHEN; Qing; (Houston, TX) ; WHEELER; Thomas
J.; (Houston, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CONOCOPHILLIPS COMPANY |
Houston |
TX |
US |
|
|
Family ID: |
56087592 |
Appl. No.: |
14/956030 |
Filed: |
December 1, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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62086035 |
Dec 1, 2014 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 43/164 20130101;
E21B 43/166 20130101; E21B 43/305 20130101; E21B 43/2408
20130101 |
International
Class: |
E21B 43/24 20060101
E21B043/24; E21B 43/16 20060101 E21B043/16 |
Claims
1. A process for producing hydrocarbons where the process
comprises: a) a reservoir having a good quality pay overlaid by
relatively poorer quality pay; b) a horizontal wellpair comprising
an injection well and a production well; c) one or more infill
production wells; d) initially injecting steam through said
injection well; e) establishing thermal communication between the
thermal chamber and one or more infill production wells; f)
switching to non-condensable gas (NCG) and steam injection; and g)
producing hydrocarbons wherein one or more production wells
comprise two or more fishbone ribs drilled laterally from the
production well.
2. The process of claim 1 wherein said hydrocarbons are selected
from the group consisting of heavy oil, bitumen, tar sands, extra
heavy oil, and the like.
3. The process of claim 1 wherein said NCG are selected from the
group consisting of air, carbon dioxide (CO.sub.2), nitrogen
(N.sub.2), carbon monoxide (CO), hydrogen sulfide (H.sub.2S),
hydrogen (H.sub.2), anhydrous ammonia (NH.sub.3), flue gas, and
combinations thereof
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a non-provisional application which
claims benefit under 35 USC .sctn.119(e) to U.S. Provisional
Application Ser. No. 62/086035 filed Dec. 1, 2014, entitled
"NON-CONDENSABLE GAS COINJECTION WITH FISHBONE LATERAL WELLS,"
which is incorporated herein in its entirety.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
[0002] None.
FIELD OF THE INVENTION
[0003] The present invention relates generally to producing
hydrocarbons by steam assisted gravity drainage. More particularly,
but not by way of limitation, embodiments of the present invention
include utilizing conventional horizontal wellpair configuration of
SAGD in conjunction with infill production wells the production
wells comprising two or more fishbone lateral wells to inject steam
initially and then switch to NCG-steam coinjection after
establishing thermal communication between the thermal chamber and
infill well.
BACKGROUND OF THE INVENTION
[0004] Bitumen recovery from oil sands presents technical and
economic challenges due to high viscosity of the bitumen at
reservoir conditions. Steam assisted gravity drainage (SAGD)
provides one process for producing the bitumen from a reservoir.
During SAGD operations, steam introduced into the reservoir through
a horizontal injector well transfers heat upon condensation and
develops a steam chamber in the reservoir. The bitumen with reduced
viscosity due to this heating drains together with steam condensate
along a boundary of the steam chamber and is recovered via a
producer well placed parallel and beneath the injector well.
[0005] However, costs associated with energy requirements for the
SAGD operations limit economic returns. Accumulation in the
reservoir of gaseous carbon dioxide (CO2) and/or solvent that may
be injected with the steam in some applications can further present
problems. For example, the gaseous CO2/solvent acts as a thermal
insulator impairing heat transfer from the steam to the bitumen,
decreases temperature of the drainage interface due to partial
pressure impact, and decreases effective permeability to oil as a
result of increased gas saturation.
[0006] Therefore, a need exists for methods and systems for
recovering hydrocarbons from oil sands with an efficient
steam-to-oil ratio.
BRIEF SUMMARY OF THE DISCLOSURE
[0007] This invention proposes a new in-situ oil sands/heavy oil
recovery process that combines fishbone technology and
non-condensable gas (NCG)-steam coinjection to accelerate oil
recovery and improve energy efficiency. This new process targets
mainly at reservoirs with specific geologic settings that have good
quality pay, such as clean sand, overlaid by relatively poor
quality pay, such as inclined heterolithic stratification (IHS)
layers. In those reservoirs, conventional SAGD normally yields a
high steam-oil ratio (SOR) due to the inefficient oil drainage from
IHS layers by steam. NCG-steam coinjection with the use of infill
wells in those SAGD reservoirs can efficiently enhance oil drainage
from IHS layers and reduce SOR; however, NCG-steam coinjection
cannot start until 4-8 years of SAGD operation when the thermal
communication between the steam chamber and infill producer is
established. To address such an issue, we propose the use of
fishbone well configuration, for either infill producers or SAGD
wells, or for both, to promote steam chamber lateral development
and thus allow early start of NCG-steam coinjection, resulting in
further SOR reduction and better economics. Our simulation shows
that NCG-steam coinjection can be started after only 2 years of
SAGD operation with 20% oil recovery by using fishbone well
configuration for infill producers as compared to 8 years of SAGD
operation with 40% oil recovery for the case conventional infill
producers. Better CSOR reduction is also confirmed by simulation
for the proposed process.
[0008] A process for producing hydrocarbons where the process
comprises: [0009] a reservoir having a good quality pay overlaid by
relatively poorer quality pay; [0010] a horizontal wellpair
comprising an injection well and a production well; [0011] one or
more infill production wells; [0012] initially injecting steam
through said injection well; [0013] establishing thermal
communication between the thermal chamber and one or more infill
production wells; [0014] switching to co-injection of NCG and
steam; and [0015] producing hydrocarbons the production wells
having fishbone ribs drilled laterally from the production
well.
[0016] The hydrocarbons produced include heavy oil, bitumen, tar
sands, extra heavy oil, and the like.
[0017] NCG may be air, carbon dioxide (CO2), nitrogen (N2), carbon
monoxide (CO), hydrogen sulfide (H2S), hydrogen (H2), anhydrous
ammonia (NH3), flue gas, or combinations thereof
[0018] As used herein, "bitumen" and "extra heavy oil" are used
interchangeably, and refer to crudes having less than 10.degree.
API.
[0019] As used herein, "heavy oil" refers to crudes having less
than 22.degree. API. The term heavy oil thus includes bitumens,
unless it is clear from the context otherwise.
[0020] By "horizontal production well", what is meant is a well
that is roughly horizontal (>45.degree. off a horizontal plane)
where it is perforated for collection of mobilized heavy oil. Of
course, it will have a vertical portion to reach the surface, but
this zone is typically not perforated and does not collect oil.
[0021] By "vertical" well, what is meant is a well that is roughly
vertical (<45.degree. off a vertical line).
[0022] By "injection well" what is meant is a well that is
perforated, so that steam or solvent can be injected into the
reservoir via said injection well. An injection well can easily be
converted to a production well (and vice versa), by ceasing steam
injection and commencing oil collection.
[0023] Thus, injection wells can be the same as production wells,
or separate wells can be provided for injection purposes. It is
common at the start up phase for production wells to also be used
for injection, and once fluid communication is established,
switched to production uses.
[0024] As used herein a "production stream" or "production fluid"
or "produced heavy oil" or similar phrase means a crude hydrocarbon
that has just been pumped from a reservoir and typically contains
mainly heavy oil and/or bitumen and water, and may also contain
additives such as solvents, foaming agents, and the like.
[0025] By "mobilized" oil, what is meant is that the oil viscosity
has been reduced enough for the mobilized oil to be produced.
[0026] By "steam", we mean a hot water vapor, at least as provided
to an injection well, although some steam will of course condense
as the steam exits the injection well and encounters cooler rock,
sand or oil. It will be understood by those skilled in the art that
steam usually contains additional trace elements, gases other than
water vapor, and/or other impurities. The temperature of steam can
be in the range of about 150.degree. C. to about 350.degree. C.
However, as will be appreciated by those skilled in the art, the
temperature of the steam is dependent on the operating pressure,
which may range from about 100 psi to about 2,000 psi (about 690
kPa to about 13.8 MPa).
[0027] In the case of either the single or multiple wellbore
embodiments of the invention, if fluid communication is not already
established, it must be established at some point in time between
the producing wellbore and a region of the subterranean formation
containing the hydrocarbon fluids affected by the injected fluid,
such that heavy oils can be collected from the producing wells.
[0028] By "fluid communication" we mean that the mobility of either
an injection fluid or hydrocarbon fluids in the subterranean
formation, having some effective permeability, is sufficiently high
so that such fluids can be produced at the producing wellbore under
some predetermined operating pressure. Means for establishing fluid
communication between injection and production wells includes any
known in the art, including steam circulation, geomechanically
altering the reservoir, RF or electrical heating, ISC, solvent
injection, hybrid combination processes and the like.
[0029] By "start up" what is meant is that period of time when most
or all wells are being used for steam injection in order to
establish fluid communication between the wells. Start-up typically
requires 3-6 months in traditional SAGD.
[0030] By "providing" wellbores herein, we do not imply
contemporaneous drilling. Therefore, either new wells can be
drilled or existing wells can be used as is, or retrofitted as
needed for the method.
[0031] The use of the word "a" or "an" when used in conjunction
with the term "comprising" in the claims or the specification means
one or more than one, unless the context dictates otherwise.
[0032] The term "about" means the stated value plus or minus the
margin of error of measurement or plus or minus 10% if no method of
measurement is indicated.
[0033] The use of the term "or" in the claims is used to mean
"and/or" unless explicitly indicated to refer to alternatives only
or if the alternatives are mutually exclusive.
[0034] The terms "comprise", "have", "include" and "contain" (and
their variants) are open-ended linking verbs and allow the addition
of other elements when used in a claim.
[0035] The phrase "consisting of" is closed, and excludes all
additional elements.
[0036] The phrase "consisting essentially of" excludes additional
material elements, but allows the inclusions of non-material
elements that do not substantially change the nature of the
invention.
[0037] The following abbreviations are used herein:
TABLE-US-00001 ABBRE- VIATION TERM API American Petroleum Institute
API gravity To derive the API gravity from the density, the density
is first measured using either the hydrometer, detailed in ASTM
D1298 or with the oscillating U-tube method detailed in ASTM D4052.
Direct measurement is detailed in ASTM D287. bbl barrel Cp
Centipoise CSOR Cumulative steam/oil ratio CSS Cyclic Steam
Stimulation cSt Centistokes. Kinematic viscosity is expressed in
centistokes DSG Direct Steam Generation EOR Enhanced oil recovery
ES-SAGD Expanding solvent-SAGD NCG Non-condensable gas OOIP
Original oil In place OTSG Once-through steam generator SAGD Steam
assisted gravity drainage SAGP Steam and gas push SAP Solvent
assisted process or Solvent aided process SCTR Sector recovery SF
Steam flooding SF-SAGD Steam flood SAGD SOR Steam-to-oil ratio THAI
Toe to heal air injection VAPEX Vapor extraction XSAGD Cross SAGD
where producers and injectors are perpendicular and used in an
array.
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] A more complete understanding of the present invention and
benefits thereof may be acquired by referring to the follow
description taken in conjunction with the accompanying drawings in
which:
[0039] FIG. 1 is a schematic of well configuration with fishbone
infill producer and the repeatable pattern for simulation,
[0040] FIG. 2 depicts a 3D simulation model for CMG STARS including
(a) a symmetric simulation model representing the repeatable
pattern with a half SAGD wellpair, a half fishbone infill producer,
and a fishbone rib connected from the infill producer and (b) a
rock facies in model,
[0041] FIG. 3 illustrates monthly oil production over time,
[0042] FIG. 4 illustrates oil recovery factor over time, and
[0043] FIG. 5 illustrates cumulative steam-oil ratio over time.
DETAILED DESCRIPTION
[0044] Turning now to the detailed description of the preferred
arrangement or arrangements of the present invention, it should be
understood that the inventive features and concepts may be
manifested in other arrangements and that the scope of the
invention is not limited to the embodiments described or
illustrated. The scope of the invention is intended only to be
limited by the scope of the claims that follow.
[0045] Previously, Chen, et al. (US 2014-0034296) produce
hydrocarbons by steam assisted gravity drainage with dual producers
separated vertically and laterally from at least one injector. Lo
and Chen (U.S. Ser. No 14/524,205) improve hydrocarbon recovery
utilizing alternating steam and steam-plus-additive injections.
[0046] Reservoirs containing clean sand overlaid by IHS layers of
low vertical permeability are not uncommon in the Athabasca oil
sands. Based on our recent study, this geologic setting with IHS
layers overlaying clean sand is unfavorable for SAGD processes
because of the difficulty of steam invasion into IHS layers to
drain oil without reaching saturated steam temperature. NCG,
however, can move into regions within and above IHS layers even
when the temperatures of those regions are still below steam
temperature yet high enough to mobilize in-situ viscous oil.
Coinjection of NCG with steam at the appropriate timing not only
enhances oil recovery from IHS layers but also improves energy
efficiency as a result of NCG accumulation on top of the reservoir.
The timing of NCG coinjection depends on the lateral growth of the
steam chamber and heating of bitumen in the upper layers by heat
conduction. Normally, infill producers are used in conjunction with
NCG coinjection to accelerate the oil production. The optimal
timing of NCG coinjection, according to our recent study, is the
time when the thermal communication between the steam chamber and
the infill producers is established. The typical time of SAGD
operation before NCG coinjection is 4-8 years, which is mainly
determined by the thickness and permeability of the lower clean
sand pay.
[0047] Fishbone technology can effectively increase the contact
area between horizontal intervals and reservoirs and boost oil
production. Implementation of the fishbone technology, either for
the infill producers or the SAGD injectors/producers, or both, can
significantly shorten the time of steam only injection (SAGD) prior
to NCG-steam coinjection and thereby maximizing SOR reduction
benefits and consequently economics. FIG. 1 shows one of the
fishbone technology implementations in which a fishbone infill
producer with alternating ribs is placed at the midway of two
adjacent SAGD wellpairs. The open-hole fishbone ribs are drilled
laterally from the infill producer and all the way to the wellpair
producer. These open-hole ribs effectively enhance local
permeability and allow steam to transport from the infill producer
during the preheating stage, and thereby heat up the cold bitumen
between the horizontal intervals. After preheating stage, steam is
injected through the wellpair injector. In addition to the steam
override and draining bitumen by gravity, the pressure difference
between the injector and the infill producer triggers viscous force
that pushes movable oil towards the infill producer. The lateral
movement of mobile liquid further enhances steam chamber lateral
development. After establishing early communication between the
SAGD wellpair and the infill producer, NCG, such as methane, flue
gas, air, or CO2, is coinjected with steam at a designed
concentration, varing from 0.1 mol % to 5 mol % through the SAGD
injector. The coinjected NCG can invade into the upper layers whose
temperature is warm enough to make bitumen mobile while not hot
enough, i.e., steam temperature to allow existence of live steam.
The invasion of NCG into the upper layers provides pressure support
and triggers countercurrent flow to drainage oil without heating
the rock matrix to steam temperature. Also, as NCG accumulates in
the upper part of the reservoir, the blanket effect of NCG help
reduce significantly heat loss to overburden. The above mechanisms
of NCG result in dramatic reduction of steam oil ratios. With
continuous NCG-steam coinjection, the NCG/steam chamber grows both
vertically and laterally. In the late stage of the process, the
concentration of NCG can gradually increase to save steam while
maintain reservoir pressure.
[0048] The NCG refers to a chemical that remains in the gaseous
phase under process conditions within the formation. Examples of
the NCG include, but are not limited to, air, carbon dioxide
(CO.sub.2), nitrogen (N.sub.2), carbon monoxide (CO), hydrogen
sulfide (H.sub.2S), hydrogen (H.sub.2), anhydrous ammonia
(NH.sub.3) and flue gas. Flue gas or combustion gas refers to an
exhaust gas from a combustion process that may otherwise exit to
the atmosphere via a pipe or channel. Flue gas often comprises
nitrogen, CO.sub.2, water vapor, oxygen, CO, nitrogen oxides
(NO.sub.x) and sulfur oxides (SO.sub.x). The NCG can make up from 1
to 40 volume percent of a mixture that is injected into the
formation.
[0049] The following examples of certain embodiments of the
invention are given. Each example is provided by way of explanation
of the invention, one of many embodiments of the invention, and the
following examples should not be read to limit, or define, the
scope of the invention.
EXAMPLE 1
Simulated Oil Recovery
[0050] A 3D symmetric model representing the repeatable pattern
with SAGD wellpair and fishbone infill producer, as shown in FIG.
1, is used for simulation using CMG STARS. The model, with
dimension of 62.5 m.times.133.3 m.times.33 m, consists of a half
SAGD wellpair with a producer located at the bottom and an injector
5 m above, and a half fishbone infill producer 62 m laterally apart
from the producer. The fishbone rib connected to the infill
producer is simulated with extremely high permeability grids, as
shown in FIG. 2(a). The 3D model is the layered model with two
facies, sandstone and IHS. A 6 m IHS layer is inter-bedded in the
sandstone pay, as shown in FIG. 2(b). The Surmont average reservoir
properties are used in the simulation.
[0051] The new process is named Fishbone_SAGD+CoINJ in simulation.
After two years of SAGD operation, 1 mol % methane (CH.sub.4) is
coinjected with steam until the end of production. Three additional
cases are simulated as comparison to the Fishbone_SAGD+CoINJ case,
i.e., the Fishbone_SAGD case that operates SAGD in the same
fishbone well configuration, the SAGD+CoINJ case that uses normal
infill producer and coinjects 1 mol % CH4 after 8 years of SAGD
operation, and the SAGD case that operates SAGD in the conventional
wellpair with normal infill producer.
[0052] When comparing the coinjection timing between the
Fishbone_SAGD+CoINJ and the SAGD+CoINJ cases, it is noticed that
NCG coinjection can start after only 2 years of SAGD operation with
20% oil recovery in the Fishbone SAGD+CoINJ case, which is much
earlier than the SAGD+CoINJ case where NCG coinjection cannot start
until 8 years of SAGD operation with 40% oil recovery.
[0053] FIGS. 3 to 5 compare the simulation results of monthly oil
rate, oil recovery and cumulative steam oil ratio, respectively.
The new process outperforms the other three cases, as evidenced by
fastest oil recovery and the lowest steam-oil ratio.
[0054] In closing, it should be noted that the discussion of any
reference is not an admission that it is prior art to the present
invention, especially any reference that may have a publication
date after the priority date of this application. At the same time,
each and every claim below is hereby incorporated into this
detailed description or specification as additional embodiments of
the present invention.
[0055] Although the systems and processes described herein have
been described in detail, it should be understood that various
changes, substitutions, and alterations can be made without
departing from the spirit and scope of the invention as defined by
the following claims. Those skilled in the art may be able to study
the preferred embodiments and identify other ways to practice the
invention that are not exactly as described herein. It is the
intent of the inventors that variations and equivalents of the
invention are within the scope of the claims while the description,
abstract and drawings are not to be used to limit the scope of the
invention. The invention is specifically intended to be as broad as
the claims below and their equivalents.
REFERENCES
[0056] All of the references cited herein are expressly
incorporated by reference. The discussion of any reference is not
an admission that it is prior art to the present invention,
especially any reference that may have a publication data after the
priority date of this application. Incorporated references are
listed again here for convenience: [0057] 1. US 2014-0034296, Chen,
et al., "Well Configurations for Limited Reflux" (2014). [0058] 2.
U.S. Ser. No. 14/524,205, Lo & Chen, "Alternating SAGD
Injections," (2014)
* * * * *